Modular block retaining wall system

ABSTRACT

A modular wall block is formed with a T-shaped through-opening defining arm sections projecting from a stem portion in each surface of the block. One arm section in the upper surface of each block is dimensioned to frictionally receive fingers of a rake-like connection device which may thereby secure an end portion of sheet of reinforcing material such as a geogrid or the like, to the block. The connection device includes enlarged tabs projecting away from the fingers to engage in a different width arm section defined in the lower surface of superimposed wall blocks for positioning the front faces of the blocks in the retaining wall relative to each other in either a vertically aligned or vertically set back relationship depending upon the direction of extension of the tabs. Stair-step sections of interconnected blocks may be interleaved to form a retaining wall. Additional connection devices may be inverted to further integrate juxtaposed stair-step sections. Likewise, the sheet of reinforcing material may span a plurality of blocks in each course to secure the stair-step sections to each other. The blocks may be used as corner blocks provided with similar aesthetic patterns on a front and a side surface for forming corner portions of sections of a retaining wall extending at right angles to each other.

FIELD OF THE INVENTION

This invention relates to a modular wall block system, and,particularly, to a modular wall block system incorporating a connectordevice to integrate superimposed courses of wall blocks into a retainingwall or the like. Extended lengths of grid-like sheets of material maybe positioned between selected courses of such wall blocks to form areinforced retaining wall or the like. The wall blocks of this inventionare designed for ease in positioning and locating individual blocksrelative to each other during construction of a retaining walls and areparticularly adapted to form a corner of a retaining wall havingsections which are perpendicular to each other.

BACKGROUND OF THE INVENTION

Retaining walls are commonly used for architectural and site developmentapplications. In civil engineering structures, the wall facing mustwithstand very high pressures exerted by backfill soils. Reinforcementand stabilization of the soil backfill is commonly provided by grid-likesheet materials that are placed in layers in the soil fill behind thewall face to interlock with the wall fill soil and create a stablereinforced soil mass. Connection of the reinforcing material to theelements forming the wall holds the wall elements in place and resistssoil backfill pressures.

A preferred form of grid-like tie-back sheet material used to reinforcethe soil behind a retaining wall structure, known as an integralgeogrid, is commercially available from The Tensar Corporation ofAtlanta, Ga. ("Tensar") and is made by the process disclosed in U.S.Pat. No. 4,374,798 ("the '798 patent"), the subject matter of which isincorporated herein in its entirety by reference. However, other formsof tie-back sheet materials have also been used as reinforcing means inthe construction of retaining walls, and the instant inventive conceptsare equally applicable with the use of such materials. Regardless of theparticular tie-back, difficulties are encountered in providing a secureinterconnection between the reinforcing means and the wall elements,especially in areas of high earthquake (seismic) activity.

In a brochure entitled "Concrete Geowall Package", published by Tensarin 1986, various retaining wall structures are shown using full heightcast concrete panels. In one such retaining wall structure, short stripsor tabs of geogrid material, such as shown in the '798 patent, areembedded in the cast wall panels. On site, longer strips of geogrid areused to reinforce the wall fill, creating a stable soil mass. To connectthe geogrid tabs to the reinforcing geogrid, the strands of one portionof geogrid are bent to form loops, the loops are inserted between thestrands of the other portion of geogrid so that the loops project out ofthe second portion of geogrid, and a rod is passed through the loops onthe opposite side of the second portion to prevent the loops beingpulled back through, thereby forming a tight interconnection between thetwo portions of geogrid, sometimes referred to as a "Bodkin" joint.

Use of full height pre-cast concrete wall panels for wall-facingelements in a retaining wall requires, during construction, that thepanels be placed using a crane because they are very large, perhaps 8 by12 feet or even larger and, as a result, are quite heavy such that theycannot be readily man-handled. To avoid such problems in the use ofpre-cast wall panels other types of retaining wall structures have beendeveloped. For example, retaining walls have been formed from modularwall blocks which are typically relatively small as compared to castwall panels. The assembly of such modular wall blocks usually does notrequire heavy equipment. Such modular wall blocks can be handled by asingle person and are used to form retaining wall structures byarranging a plurality of blocks in courses superimposed on each other,much like laying of brick or the like. Each block includes a body with afront face which forms the exterior surface of the retaining wall.

Modular wall blocks are formed of concrete, commonly mixed in a batchingplant with only enough water to hydrate the cement and hold the unittogether. Such blocks may be commercially made by a high-speed processwhich provides a mold box having only sides, without a top or bottom,positioned on top of a steel pallet which contacts the mold box tocreate a temporary bottom plate. A concrete distributor box bringsconcrete from the batcher and places the concrete in the mold box andincludes a blade which levels the concrete across the open top of themold box. A stripper/compactor is lowered into the open, upper end ofthe box to imprint the block with a desired pattern and to compress theconcrete under high pressure. The steel pallet located at the bottom ofthe mold box resists this pressure.

A vibrator then vibrates the mold box to aid in concrete consolidation.After approximately 1/2 to four seconds, the steel pallet is moved awayfrom the bottom of the mold box which has been positioned above aconveyor belt. The stripper/compactor continues to press on the formedconcrete to push the modular wall block out of the mold box onto theconveyor belt. This process takes about seven to nine seconds tomanufacture a single wall block. The formed wall block is cured forapproximately one day to produce the final product.

With this high-speed method of construction, it is not practical toembed short strips or tabs of grid-like material in the blocks in themanner of the pre-cast wall panels shown in the Tensar brochure toenable interconnection with a grid-like reinforcing sheet materialdirectly or by a Bodkin-type connection or the like. Therefore, othermeans for securing the reinforcing grid to selected modular blocks usedto construct a retaining wall have had to be devised.

In an attempt to provide alternative means for securing the reinforcinggrid to selected modular block, a modular wall block system as disclosedin copending U.S. application Ser. No. 08/254,710, filed Jun. 6,1994,now U.S. Pat. No. 5,540,525, commonly associated with the instantapplication and incorporated herein in its entirety by reference, hasbeen developed. The upper surface of the wall blocks in the system ofthe '710 application is recessed to accommodate the end portions of asheet of grid-like reinforcing material and a groove is formed acrossthe recessed portion, parallel to, and set back from, the front face. Aplurality of spaced teeth or fingers projecting from a common spine orcross bar of a comb-like grid connection device are passed downwardlythrough the apertures on the end portions of the grid sheet andfrictionally engaged in the groove to positively secure the grid to theblock without reliance on the weight of a superimposed course of blocks.Thus, the grid-like sheet of material is securely retained by the gridconnection device even in the event of a vertical acceleration of thewall blocks which may occur during an earthquake or the like.

The grid connection device may be formed of steel, aluminum, fiberglass,a plastic reinforced with fiberglass or, preferably, a high strengthpolymer. The fingers may be provided with serrations to enhance thefrictional engagement with the sidewalls of the groove in the wall blockand lock the connection device in place. Thus, load is transferred fromthe grid-like sheet of material through the fingers and spine of theconnection device to the modular wall block.

An improved modular wall block system is disclosed in commonly assigned,copending U.S. application Ser. No. 08/370,324, filed Jan. 10, 1995,also incorporated herein in its entirety by reference. In addition tothe groove in the upper surface of the wall blocks of the '324application, a slot is formed in the lower surface, parallel to, and setback from, the front face. The slot in the lower surface is wider thanthe groove in the upper surface. In this system the comb-like gridconnection device is also provided with a plurality of spaced tabs whichextend upwardly from the spine to slidingly engage in the slots ofsuperimposed wall blocks when the retaining wall is being built. Thetabs are wider than the fingers in a direction transverse to the spine.Thus, if one edge of the fingers are aligned with one edge of the tabs,the other edge of the tabs extend beyond the other edge of the fingers.As described in detail in the '324 application, by properly dimensioningthe tabs vis-a-vis the set back of the slot, the front faces ofsuperimposed courses of wall blocks in a retaining wall may selectivelybe vertically aligned or stepped back by turning the grid connectiondevice 180° about a vertical axis in use.

SUMMARY OF THE INVENTION

It is, therefore, a primary object of this invention to provide a simpleand inexpensive modular wall block system formed of a plurality of wallblocks and including a connection means for selectively verticallyaligning or setting back the front faces of superimposed courses of wallblocks, where the connection means may also positively secure extendedlengths of grid-like reinforcing sheet material to the wall blocks, ifdesired.

A further object of this invention is the provision of such a modularwall block system where the wall blocks each have a through-openingextending between their upper and lower surfaces to define, respectivelya groove for reception of fingers of a connection device in at least theupper surfaces and a slot for reception of the tabs of the connectiondevice in at least the lower surfaces.

Still another object of the invention is the provision of modular wallblocks having a T-shaped through-opening wherein the cross-bar of the Tis formed of two arms of unequal width measured in a direction from thefront to the rear of the wall blocks. The arm of less width is designedto fractionally receive the fingers of a connection device in at leastan upper surface of a lower tier wall block. The wider arm slidinglyreceives the locating tabs of a connection device in at least the lowersurface of an upper tier or superimposed wall block. For ease ofmanufacture, each block may be initially formed with a slight taper withthe side walls diverging upwardly so the formed concrete wall block maybe easily pressed downwardly by the stripper/compactor to free the samefrom a tapered core or molding element fixed within the mold box duringmanufacture of the block.

Thus, according to a preferred embodiment of the instant inventiveconcepts, a wall block according to this invention, useful in formingthe corner of a retaining wall having perpendicularly extendingsections, includes a through-opening spaced inwardly from the frontface, rear face and side walls of the block to receive short sections ofconnection devices in arms formed by the through-opening.

As indicated, a preferred grid-like sheet reinforcing material may bemade according to the techniques disclosed in the above-identified '798patent. Preferably, uniaxially-oriented geogrid materials as disclosedin the '798 patent are used, although biaxial geogrids or grid materialsthat have been made by different techniques such as woven, knitted ornetted grid materials formed of various polymers including thepolyolefins, polyamides, polyesters and the like or fiberglass, may beused. In fact, any grid-like sheet material, including steel (weldedwire) grids, with interstitial spaces capable of being secured toselected modular wall blocks with the connection device of the instantinvention in the manner disclosed herein are suitable. In addition, itis possible that felt-like fabrics, including woven or non-woven, solidor perforated geofabrics, geonets, or even composite materials includingsome form of geofabric and/or geogrid laminates may be used as thereinforcing material according to this invention. All of such materialsare sometimes referred to herein and in the appended claims as"grid-like sheets of material", whether they are formed with apertures,or not.

With the preferred reinforcing material of the '798 patent, a highstrength geogrid is formed by stretching an apertured plastic sheetmaterial. Utilizing the uniaxial techniques, a multiplicity ofmolecularly-oriented elongated strands and transversely extending barswhich are substantially unoriented or less-oriented than the strands,are formed. The strands and bars together define a multiplicity of gridopenings. With biaxial stretching, the bars are also formed intooriented strands. In either event, or when using other aperturedgrid-like sheets of material, the fingers of the grid connection deviceare spaced apart equal to a spacing between strands of the grid-likesheet of material, but may also be spaced apart several times thespacing between strands of the grid-like sheet of material such thatsome, but not necessarily every, grid opening receives a finger.

If the "grid-like" reinforcing sheets are not initially formed withapertures such as in a geofabric or the like, the fingers of theconnection device may be used to actually puncture or perforate thesheet in use to secure the same to the modular wall blocks of theinvention. In fact, it will be readily recognized that the sheetmaterial need not even be perforated to produce a secure attachment tothe modular wall blocks; the groove in the block and the fingers of theconnection device can be dimensioned to wedge a section of thereinforcing sheet in the groove when the fingers of the connectiondevice are driven into the groove.

At a construction site, a plurality of modular wall blocks are commonlystacked in laterally staggered, vertically superimposed, courses. Whenconstructing a retaining wall of limited height, generally less than sixfeet, and usually straight, such as may be formed in a residentialsetting, the fingers of the connection device may be secured within theone (narrower) arm of the T-shaped through-opening on the upper surfaceof each block. The other (wider) arm defined by the T-shaped other endof the through-opening in the lower surface of superimposed wall blocksmay cooperate with the upwardly projecting tabs on the connectiondevice. The locating tabs may selectively form a retaining wall wherethe front faces of the stacked courses of wall blocks are verticallyaligned or vertically set-back depending upon the orientation of theconnection device. Such a construction would produce juxtaposed sectionsof the retaining wall comprising superimposed, laterally staggered, wallblocks interconnected in stair-step fashion, with the blocks of suchsections resting on each other to integrate the sections into acontinuous retaining wall by the effect of gravity.

Alternatively, additional connection devices may be used to fixedlysecure the stair-step sections to each other by driving the fingers of aconnection device into the narrower arm of the T-shaped through-openinglocated in the lower surface of superimposed wall blocks. The tabs ofsuch additional connection devices, now downwardly projecting, wouldseat in the wider arm of the upper surface of a successively lowercourse of wall blocks in a juxtaposed stair-step section. Each wallblock would thereby be engaged with at least two other wall blocks whensuccessive courses of wall blocks are laid to build a retaining wall.

For walls of greater height, or where desired, the fingers of theconnection device may be secured in selected blocks so as to capture theend portions of elongated lengths of grid-like sheets of reinforcingmaterial, either by passing through preformed apertures in suchreinforcing material, forming perforations in situ, or merely wedgingthe end portions in the block openings, the remainder of the reinforcingsheet being stretched out and interlocked with the fill soil oraggregate behind the retaining wall. In this manner, the sheets ofgrid-like sheet of material reinforce the fill so as to create a stablemass behind the retaining wall. Moreover, if the sheets of grid-likematerial span several adjacent wall blocks in a course of wall blocks,the adjacent stair-step sections would be laterally inter-connected bythe grid-like sheets, without the need for additional connection devicesas described in the alternative embodiment described above.

Other forms of modular wall blocks which may be used as corner blocksare disclosed in commonly assigned U.S. application Ser. No. 08/591,319,filed simultaneously herewith in the name of Joseph S. Bailey, II, etal. the disclosure of which is incorporated herein in its entirety byreference.

The modular wall block according to the present invention may includesubstantially flat upper and lower surfaces with a single T-shapedthrough-opening defining a centrally located stem with arms of differentwidths forming the cross-bar of the T and the grooves or slots of theblock. The wall block is preferably about 75/8 inches high, 18 incheswide and 8 inches deep. These blocks may be used as corner blocks incombination with other types of wall blocks or they may be used to formretaining walls, generally of limited height, by themselves, with orwithout grid-like reinforcing material.

The modular wall blocks of this invention are preferably molded asdouble blocks, and then split transversely to form a roughened or jaggedexterior facing for aesthetic reasons. To form a jagged exterior face ata corner surface, a side portion of the block can be broken away in thesame way.

The above and other objects of the invention, as well as many of theattendant advantages thereof, will become more readily apparent whenreference is made to the following detailed description, taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a molded double wall block which, when split,forms two separate wall blocks with jaggered front faces, and whichincludes additional splitting grooves to form a jagged side surface whenthe block is used as a corner block.

FIG. 2 is a sectional view taken along line 2--2 of FIG. 1.

FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 1.

FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 1.

FIG. 5 is a cross-sectional view taken along line 5--5 of FIG. 1.

FIG. 6 is a perspective view of a connection device for use inconnection with the wall blocks of the present invention so as tovertically align or offset the front faces of superimposed courses ofwall blocks.

FIG. 7 is a cross-sectional view taken along line 7--7 of FIG. 6.

FIG. 8 is a schematic plan view of one embodiment of a retaining wallformed entirely of modular wall blocks according to this invention, theretaining wall including perpendicularly extending portions defining aright-angled corner, with laterally off-set superimposed blocks beinginterconnected by short comb-like connector devices to form adjacentstair-step sections which rest on each other by gravity to produce acontinuous wall and with one of the blocks shown in phantom as offsetrearwardly from the other blocks to step back the front faces ofsuperimposed courses of blocks, if desired.

FIG. 9 is a cross-sectional view taken along line 9--9 of FIG. 8.

FIG. 10 is a view similar to FIG. 9, with inverted connection devicesinterconnecting laterally offset, superimposed wall blocks to furtherintegrate the retaining wall.

FIG. 11 is a view similar to FIG. 9 with sections of a grid-like sheetmaterial spanning a plurality of wall blocks in each course of wallblocks to integrate the resultant retaining wall.

FIG. 12 is an enlarged fragmentary sectional view of end portions of auniaxially oriented geogrid secured to the top surface of a wall blockmade in accordance with this invention.

FIG. 13 is a plan view, with a section taken of the connection device,to illustrate the fingers of the connection device passing through theopenings in end portions of a sheet of geogrid to secure the geogrid toa top surface of a wall block.

FIG. 14 is a perspective view of a portion of a hybrid retaining wallhaving perpendicularly extending sections formed primarily of basic wallblocks according to the '324 application referred to above, with thewall blocks of the present invention used as corner blocks.

FIG. 15 is a fragmentary plan view of a portion of the retaining wallshown in FIG. 14, illustrating the interconnection of the wall blocks atthe corner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In describing preferred embodiments of the invention as illustrated inthe drawings, specific terminology will be used for the sake of clarity.However, the invention is not intended to be limited to the specificterms so selected, and it is to be understood that each specific termincludes all technical equivalents which operate in a similar manner toaccomplish a similar purpose. Further, while preferred dimensions areset forth to describe the best mode currently known for the modular wallblock system of this invention, these dimensions are illustrative andnot limiting on the instant inventive concepts.

While a retaining wall formed by assembling a multiplicity of modularwall blocks according to this invention is shown in some of the drawingsas providing a vertical exterior facing surface, as is well known,succeeding courses of modular wall blocks are commonly shifted slightlyrearwardly for stability and appearance. As explained in more detailbelow, the instant inventive concepts readily enable the construction ofa retaining wall having either design.

While the preferred embodiment hereof is shown and described withreference to a uniaxially-oriented polymer geogrid such as is disclosedin the '798 patent, alternative grid-like tieback reinforcing sheetmaterials may be substituted therefor, including grid-like sheetmaterials manufactured using weaving, knitting or netting techniques,steel (welded wire) grid, geonets, geofabrics, solid sheet materials orcomposites may be used as well.

With reference now to the drawings in general, and FIGS. 1 through 5 inparticular, a preferred embodiment of a modular wall block as castaccording to this invention is shown. It is common practice to initiallymold double blocks designated generally by the reference numeral 20.

Since the dimensions of the T-shaped openings formed in each surface ofthe individual wall blocks 24 resulting from splitting a double wallblock 20, are only mominally different as a result of the slight taperof the through-opening which facilitates manufacturing the blocks, theblocks may be used with either side up in constructing a retaining walltherefrom.

Double block 20 is molded with a peripheral groove 22, which may beimpacted with a chisel or pointed device (not shown) to split the doubleblock 20 apart to form the pair of modular wall blocks 24. Each of thethus formed wall blocks will have an aesthetic jagged front face 26.

Each wall block 24, in addition to the front face 26, includes a rearface 28, parallel to the front face 26, parallel side walls 30, 32, alower surface 34 (which could be the upper surface of the wall block inuse), and an upper surface 36. The lower and upper surfaces 34 and 36,also extend parallel to each other.

If the wall blocks 24 are to be used as corner blocks each block isprovided with a further groove 38 extending from the rear face 28 towardthe front face 26 to form a jagged side face 40 for aesthetic continuityof the retaining wall surface as will discussed below with particularreference to FIG. 14. If the blocks are to be used in non-cornerpositions, either the end section 42 is not removed, the wall blocks aremolded without this section, or special considerations are made whenassembling a wall of the blocks to provide for proper positioning ofmechanical connections between superimposed courses. End sections can beprovided on either side of the center line of the wall block 24 forforming opposite corners of a retaining wall, but this is not generallynecessary since the wall blocks 24 may simply be inverted to present thejagged face 40 at either side.

A T-shaped through-opening 44 extends through each block 24 betweensurfaces 34 and 36. Through-opening 44 terminates in T-shaped apertures46, 48 in the surfaces 34, 36, respectively. The T-shaped aperture ineach surface includes a stem section 50 and a pair of arm sections 52,54 defining the cross-bar of the T.

The width of the arm sections 52 and 54 is measured in a direction fromthe front face 26 towards the rear face 28 of the blocks 24. The armsections 52 are of a width (from front to rear) of approximately 0.52inches at the surface 34 and 0.78 inches at surface 36. The arm sections54 are a width (from front to rear) of approximately 1.625 inches atsurface 34 and 1.825 inches at surface 36. The differences in widths foreach of the arm sections 52,54 at the surfaces 34 and 36 is attributableto a slight taper of the mold elements or core used to form the T-shapedthrough-opening 44 so that the molded blocks are easily pushed off ofthe mold elements during manufacture. The stem sections 50 are about5.72 inches long (from side to side) and 3.8 inches wide at surface 34and 5.92 inches long and 4.0 inches wide at surface 36.

In the lower and upper surfaces 34 and 36, the arm sections 52 define agroove which is parallel to, and set back from, the front face 26.Likewise, in the lower and upper surfaces 34 and 36, the arm sections54, define a slot which is parallel to, and set back from, the frontface 26. The groove and slot in the wall block interact with the fingersand tabs of a connecting device to interconnect superimposed wallsblocks in a retaining wall, secure a geogrid or the like thereto, ifdesired, and selectively position the front faces of stacked courses ofwall blocks in a vertical or stepped back orientation. Additionally,since the side surfaces of the wall blocks 24 are perpendicular to thefront, and are continuous, i.e., the grooves and slots do not extend tothe side surfaces, they may be provided with a jagged surface like thefront face and can be effectively used to form corners in a retainingwall having portions extending at right angles to each other withaesthetically compatible facings.

Referring now in more detail to the blocks 24, the stem section 50 ofthe T-shaped through-opening 44 includes two parallel side walls 56interconnected with the front wall of parallel front and rear walls 58of the arm sections 52 of the groove at right angle intersections 60 andthe front wall of parallel front and rear walls 62 of the arm sections54 of the slot at right angle intersections 64.

The stem section 50 includes front wall 66 and rear wall 68. The stemsection of the through-opening 44 lightens the block and facilitateslifting and placing blocks in constructing a retaining wall.

Details of one form of a preferred connection device are shown at 70 inFIGS. 6 and 7. The connection device 70 includes a plurality of fingers72 extending substantially parallel to each other and interconnected atone end by a spine 74. For use with the wall block of this invention,the length of the spine 74 is preferably equal to, or less than, thelength of the arm 52, which in the preferred embodiment is about 3inches. The fingers 72 of the grid connection device 70 may be spacedapart by a distance equal to, or a multiple of, the spacing between theopenings 76 formed by bars 94 and strands 96 of a uniaxially orientedgeogrid 92 as seen particularly in FIGS. 12 and 13. Obviously, otherspacing may be appropriate if different grid-like sheets of reinforcingmaterials are used.

As shown in detail in FIG. 7, the fingers 72 preferably include lateralsidewalls 82, which include, proceeding downwardly from spine 74, aplurality of spike projections 84. Spike projections 84 extendapproximately 1/16 inch beyond the sidewalls 82 of the fingers 72. Eachspike projection 84 has an overall height of approximately 3/16 inch. InFIG. 12, the spike projections 84 are schematically shown engaging asidewall 58 of arm section 52.

Due to the resilient nature of the material of the connection device 70,the spike projections 84 are driven downwardly along the sidewalls 58 ofthe arm section 52 for frictional engagement with the sidewalls 58. Bythe angle of inclination of the spike projections 84, it is possible todrive the fingers 72 downwardly into the groove 42 whereas considerableforce would be required to extricate the connection device 70 from thegroove 42.

If the reinforcing sheet is imperforate, the fingers 72 may be sharpened(not shown) to puncture the sheet in use. Alternatively, the sheet maybe wedged into the groove by the fingers (also not shown) in an obviousmanner.

Spaced across the connection device 70 on a side of the spine 74opposite to that of the downwardly projecting fingers 72 are upwardlyextending locating tabs 80. A tab 80 preferably extends above the spine74 in alignment with a majority of the downwardly projecting fingers 72,although the tabs 80 need not be aligned with the fingers 72 and forsome applications only a limited number of tabs may be desirable.Further, the tabs 80 may form a single bar (not shown) connected to anupper end of the fingers 72, thereby avoiding the need for a spine.

Preferably, an overall width of the tab 80 is 1.375 inches. Incombination, the height of the connection device from the top of the tab80 to the bottom of the finger 72 is approximately 2.125 inches.

The tabs 80, in the preferred embodiment, include one lateral edge 88 inalignment with one lateral edge of the fingers 72. It is also possiblefor the lateral edges 88 of the tabs 80 to be offset inwardly oroutwardly from the lateral edges of the fingers 72. However, theopposite lateral edges 90 of the tabs 80 projects beyond the otherlateral edges of the fingers 72 by a distance approximating thedifference in width between the arm section 52 and the arm section 54.This relationship may be defined by central axis "c" of the fingers 72being laterally offset from central axis "d" of the tabs 80 by about 1/2that distance.

In constructing a retaining wall 110, such as shown in FIGS. 8 and 9, aplurality of modular wall blocks according to this invention arepositioned side by side in the usual manner to form a first course 110a.The fingers 72 of a connecting device 70 are secured in the arm section52 in the upper surfaces 34 of each wall block with the offset portionof the tab 80 facing forwardly if the front faces of the wall blocks inthe retaining wall are to be vertically aligned. Alternatively, if thefront faces are to be stepped rearwardly, the fingers 72 of theconnection devices 70 are engaged in the arm section 52 with the offsetportions of the tabs 80 facing rearwardly.

Thus, the direction of the offset portion or extension of the tabs 80 ofthe connection devices 70 selectively aligns the front faces 26 ofsuccessive courses 110b, 110c in a retaining wall 110 produced with thewall block system of this invention in a vertically aligned orvertically staggered orientation. More specifically, the rear wallportion of the arm sections 54 located at the bottom of a successivelyhigher course of wall blocks is engaged against edge 88 of tabs 80 whenthe front faces of successive courses of wall blocks are to bepositioned in a vertically aligned orientation or against edge 90 oftabs 80 when the front faces of successive courses of wall blocks are tobe positioned in an offset or vertically staggered orientation.

Since the wall blocks 24 are commonly laterally staggered in stackedcourses as seen at 110a, 110b, 110c, the length of the connection device70, shown in FIG. 6, will be such as to fit within the superimposedportions of the grooves and slots in vertically juxtaposed blocks. Morespecifically, when the fingers 72 of the connection device 70 are driveninto the arm sections 52 to engage the side walls 58, the connectiondevice 70 must fit within the arm sections 52. The upwardly extendinglocating tabs 80 of the connection device 70 project then above surface34 of a lower course of wall blocks 24 and are accommodated within thearm sections 54 of blocks 24 in an upper course. Since individual blocksin successive courses of the blocks are laterally staggered with respectto a successively lower course of wall blocks, the connection devices 70must be carefully positioned within the arm sections 52 so as to alignwith the arm sections 54 on a successively higher course of wall blocks.

In the embodiment of FIGS. 8 and 9, each wall block 24 is only connectedto one superimposed wall block by a connection device 70, with no directconnection between adjacent wall blocks in a course of wall blocks orother superimposed wall blocks in a higher course. Sections of wallblocks connected in a stair-step pattern may then be interfitted to reston each other by gravity in the formation of a retaining wall. Such aconstruction is quite acceptable for many applications, particularlywith retaining walls of relatively low height.

For the construction of retaining walls of increased height, a retainingwall 120 as shown in FIG. 10 may be constructed. Retaining wall 120 mayinclude a similar interconnection between superimposed blocks in courses120a, 120b and 120c, for example, as shown in FIG. 9 using connectordevices 70a in a stair-step fashion. However, in FIG. 10, additionalconnector devices 70b are used which are opposite in orientation tothose of connector devices 70a. In this embodiment, a connector device70b is inverted and the fingers 72b of the connector device are driveninto the arm section 52 in the lower surface 36 of a wall block 24.Accordingly, when the wall block is set in a staggered, offsetrelationship with respect to the wall blocks of a successively lowercourse of wall blocks, tabs 80a of connector device 70a extend upwardlyinto arm section 54 in the lower surface 36 of a wall block and the tabs8Ob of a connector device 70b extend downwardly into the arm section 54in an upper surface 34 of a successively lower wall block.

As shown in FIG. 10, each wall block above the lowermost course 120a andbelow the uppermost course 120c in the retaining wall 120, is secured totwo different wall blocks in a successively lower course of wall blocksand to two different wall blocks in a successively higher course of wallblocks. The additional interconnections between wall blocks, over thoseshown in FIG. 9, provides additional strength to the retaining wall,facilitating an increased height.

In the embodiment of FIGS. 11-13, retaining wall 130 is constructedusing connection devices 70 in the manner illustrated in the retainingwall 110 shown in FIG. 9. However, as will be seen in FIG. 11, grid-likesheets of material 92 are placed across the upper surfaces 34 of aplurality, preferably at least three, wall blocks 24 and secured inplace by the fingers of the grid connectors as described herein.

The grid-like sheet of material thus acts to strengthen the connectionbetween adjacent wall blocks in a given course as well as successivelyhigher courses of wall blocks, so that, e.g., the stair-step sections ofthe retaining wall 130 are interconnected via the connection of the gridmaterial by the connector devices 70.

If the reinforcing sheet material is a uniaxially oriented geogrid asshown at 92 in FIGS. 12 and 13, the geogrid is placed on the uppersurface 34 of a plurality of blocks 24, with a transverse bar 94forwardly of the arm sections 52 and the strands 96 spanning the armsections 52. The fingers 72 of a connection device 70 pass through theapertures 76 of the geogrid and the spine or crossbar 74 captures theend portions of the geogrid and fixedly secures the same to the modularwall block with the remainder of the grid-like sheet of material 92extending rearwardly from the block 24 into the soil or otherparticulate material 98 as best seen in FIG. 13.

The area behind the rear faces 28 of the blocks 24 is progressivelybackfilled with soil or other aggregate 98 as the courses are laid tosecure the extended lengths of sections of grid-like sheet of material92 within the fill material 98. The grid-like sheet of material 92functions to reinforce the fill 98 and thereby create a contiguous massin a well known manner.

The tabs 80 and spine 74 of the connection device 70, and all portionsof the grid-like sheet of material 92 passing over the upper surface 34of the block 24, are above the level of the upper surface 34 of theblock 24. By the arrangement of connection devices 70, shown in FIG. 11,the grid-like sheet of material 92 interconnects at least three adjacentblocks 24, for example, in a course of blocks. Superimposed courses ofstaggered blocks 24 with grid-like sheets of material 92, serves to tietogether the courses of blocks of the thusly-formed retaining wall 130.

The section of grid-like sheet of material 92 illustrated in thedrawings is representative of an extended length of grid-like sheet ofmaterial which is to be secured to a modular wall block 24 and typicallymeasures four feet wide in the direction of the junction bars 94, andanywhere from four to twenty-five feet or more in length in thedirection of the longitudinal axis of the strands 96.

As is usual and customary in the industry in the construction of aretaining wall, after the laying of several courses of wall blocks, thecourses are shimmied to be level to accommodate the placement of sheets92 of grid-like material between courses of blocks and any variancesfrom acceptable tolerances in the construction of the wall blocks. Thewidth of the arm section 54 is intended to be approximately 1/4 of aninch wider than the width of the tab 80 to allow some play in thepositioning of a successively higher course of modular wall blocks andto permit superimposed wall blocks, which are usually laterallystaggered with respect to the blocks in a lower course, to be easilyslid sideways during construction.

In FIGS. 14 and 15 a hybrid retaining wall is schematically shown at 150including a multiplicity of wall blocks 24 as described with referenceto FIGS. 1-5, used to form a right-angled corner portion of theretaining wall, in combination with basic wall blocks 152 of the typedisclosed in the aforementioned '324 application.

The straight portions of the retaining wall 150 are formed byinterconnecting wall blocks 152 with appropriately sized connectordevices 70, with or without sections of geogrid or the like (not shown).Where the corner blocks 24 are used, the teeth of a shortened connectordevice 70a is secured in a groove 154 of a wall block 152 with the tabsprojecting upwardly into the arm section 54 at the lower surface 34 of asuperimposed block 24 to anchor the blocks adjacent to the corner of theretaining wall. It may be desirable to insert a bar as shown at 160 inthe direction of arrow 162 through the superimposed portions of armsections 52, 54 of successively lower blocks until the ground is engagedso as to interconnect the blocks 24 at the corner of wall 150.

Alternatively, as shown in FIG. 15, a grid connector 70a fixed in an armsection 52 of a corner block 24a projects upwardly so that the tabs ofthe connector device fit within the stem portion 50 of superimposedblock 24b. By the proper dimensioning of the wall blocks 24, connectordevices 70a can be used to interlock successively superimposed cornerblocks in retaining wall 150.

Having described the invention, many modifications thereto will becomeapparent to those skilled in the art to which it pertains withoutdeviation from the spirit of the invention as defined by the scope ofthe appended claims.

I claim:
 1. A modular wall block comprising:a front face, a rear face,an upper surface, a lower surface, and opposed sidewalls defining sidefaces extending between said upper and lower surfaces and said front andrear faces, a first opening defined in each of said upper and lowersurfaces parallel to, and spaced rearwardly of, said front face forreceiving portions of a connector device, and a second opening definedin each of said surfaces parallel to, and spaced rearwardly of, saidfront face, for receiving other portions of the connector device so asto position the front faces of a superimposed course of wall blocks withrespect to each other in one of a vertically aligned and vertically setback orientation, said first and second openings being at leastpartially defined by opposite ends of a through-opening extending fromsaid upper surface of said block to said lower surface, said firstopenings at each of said surfaces being of different front to rearwidths from said second openings, said first and second openingsextending in opposite directions from a central stem section.
 2. Amodular wall block as claimed in claim 1 to be used as a corner block informing a retaining wall having sections extending at right angles toeach other, wherein said front face and at least one side face extend atright angles to each other.
 3. A modular wall block as claimed in claim2, wherein said front face and said at least one side face each includesimilar aesthetic patterns formed therein.
 4. A modular wall blocksystem to be used for forming a retaining wall, said modular wall blocksystem comprising:a plurality of wall blocks each having a front facefor forming a portion of an exterior surface of the retaining wall, arear face, upper and lower surfaces, and opposed sidewalls defining sidefaces extending between said upper and lower surfaces and said front andrear faces, connector devices for interconnecting superimposed coursesof said wall blocks with successively lower courses in the retainingwall, a first opening defined in each of said surfaces of each wallblock parallel to, and spaced rearwardly of, said front face forreceiving first portions of a connector device when the retaining wallis built, and a second opening defined in each of said surfaces of eachwall block parallel to, and spaced rearwardly of, said front face forreceiving other portions of said connector device when the retainingwall is built so as to position the front faces of superimposed coursesof wall blocks with respect to each other in one of a vertically alignedand vertically set back orientation, said first and second openings ineach wall block being at least partially defined by opposite ends of athrough-opening extending from said upper surface of said block to saidlower surface, said first opening at each of said surfaces being ofdifferent front to rear widths from said second opening.
 5. A modularwall block system as claimed in claim 4 wherein, said through-opening isT-shaped and defines T-shaped apertures in each of said surfaces, eachT-shaped aperture including a central stem section extending toward saidfront and rear faces of said block, and said first and second openingsbeing defined by arm sections extending outwardly from a front end ofsaid stem section parallel to said front face and toward respectivesidewalls of said block.
 6. A modular wall block system as claimed inclaim 4 wherein at least some of said wall blocks are corner blocks tobe used for forming a retaining wall having sections extending at rightangles to each other, at least said corner blocks include a front faceand at least one side face extending at right angles to each other, eachof which define portions of the respective sections of a retaining wallface.
 7. A modular wall block system as claimed in claim 6, wherein saidfront face and said at least one side face of said corner blocks includesimilar aesthetic patterns formed therein.
 8. A modular wall blocksystem as claimed in claim 4, wherein said first portions of saidconnector device includes a plurality of finger members and said otherportions of said connector device include at least one tab extendingaway from said finger members, a central axis of said finger membersbeing spaced from a central axis of said at least one tab.
 9. A modularwall block system as claimed in claim 4, further comprising a sheet ofreinforcing material having end portions to be secured to selected wallblocks with the remainder of the sheet of reinforcing material extendingrearwardly into fill material behind the retaining wall to reinforce theretaining wall when the retaining wall is built.
 10. A modular wallblock system as claimed in claim 9, wherein said end portions of saidsheet of reinforcing material defines a plurality of laterally spacedopenings, said first portions of said connector device to be passedthrough said spaced openings of said sheet of reinforcing material to befrictionally received in said first opening in said upper surface ofsaid selected wall blocks with additional portions of said connectordevice overlying portions of said sheet of reinforcing material andthereby securing said sheet of reinforcing material to said selectedwall blocks.
 11. A retaining wall comprising:a plurality of courses ofsuperimposed wall blocks, each wall block having a front face forming aportion of an exterior surface of the retaining wall, a rear face, upperand lower surfaces, and opposed sidewalls defining side faces extendingbetween said upper and lower surfaces and said front and rear faces,connector devices interconnecting superimposed wall blocks tosuccessively lower wall blocks, a first opening defined in each of saidsurfaces of each wall block parallel to, and spaced rearwardly of, saidfront face, first portions of a connector device frictionally receivedin said first opening in the upper surface of each wall block, a secondopening defined in each of said surfaces of each wall block parallel to,and spaced rearwardly of said front face, other portions of saidconnector opening received in said second opening in the lower surfaceof each wall block so as to position the front faces of superimposedcourses of wall blocks with respect to each other in one of a verticallyaligned and vertically set back orientation, said first and secondopenings in each wall block being at least partially defined by oppositeends of a through-opening extending from said upper surface of saidblock to said lower surface, said first openings at each of saidsurfaces being of different front to rear widths from said secondopening, and fill material located behind said rear face of said wallblocks for reinforcing said retaining wall.
 12. A retaining wall asclaimed in claim 11 having sections extending at right angles to eachother, at least some of said wall blocks being corner blocks, at leastsaid corner blocks including a front face and at least one side faceextending at right angles to each other, each of which define portionsof said respective sections of the retaining wall.
 13. A retaining wallas claimed in claim 12, wherein said front face and said at least oneside face of said corner blocks include similar aesthetic patternsformed therein.
 14. A retaining wall as claimed in claim 11, whereinsaid through-opening is T-shaped and defines T-shaped apertures in eachof said surfaces, each T-shaped aperture including a central stemsection extending toward said front and rear faces of said block, andsaid first and second openings being defined by arm sections extendingoutwardly from a front end of said stem section parallel to said frontface toward respective sidewalls of said block.
 15. A retaining wall asclaimed in claim 11, wherein said first portions of said connectordevice includes a plurality of finger members and said other portions ofsaid connector device include at least one tab extending away from saidfinger members, a central axis of said finger members being spaced froma central axis of said at least one tab.
 16. A retaining wall as claimedin claim 11, further comprising a sheet of reinforcing material havingend portions secured to selected wall blocks with the remainder of thesheet of reinforcing material extending rearwardly into said fillmaterial behind the retaining wall to reinforce the retaining wall. 17.A retaining wall as claimed in claim 16, wherein end portions of saidsheet of reinforcing material defines a plurality of laterally spacedopenings, first portions of said connector device passing through saidspaced openings of said sheet of reinforcing material and frictionallyreceived in said first opening in said upper surface of said selectedwall blocks, additional portions of said connector device overlyingportions of said sheet of reinforcing material and thereby securing saidsheet of reinforcing material to said selected wall blocks.
 18. Aretaining wall as claimed in claim 16, wherein each sheet of reinforcingmaterial is connected to a plurality of laterally juxtaposed wall blocksin a course of wall blocks.
 19. A retaining wall as claimed in claim 11,further including additional connector devices,said first portions ofsaid additional connection devices being received in said first openingin said lower surface of each wall block, and said other portions ofsaid additional connection devices being received in said second openingin said upper surface of each wall block.
 20. A modular wall blockcomprising:a front face, a rear face, an upper surface, a lower surface,and opposed sidewalls defining side faces extending between said upperand lower surfaces and said front and rear faces, a first openingdefined in each of said upper and lower surfaces parallel to, and spacedrearwardly of, said front face for receiving portions of a connectordevice, and a second opening defined in each of said surfaces parallelto, and spaced rearwardly of, said front face, for receiving otherportions of the connector device so as to position the front faces of asuperimposed course of wall blocks with respect to each other in one ofa vertically aligned and vertically set back orientation, said first andsecond openings being at least partially defined by opposite ends of athrough-opening extending from said upper surface of said block to saidlower surface, said first openings at each of said surfaces being ofdifferent front to rear widths from said second openings, saidthrough-opening being T-shaped and defining T-shaped apertures in eachof said surfaces, each T-shaped aperture including a central stemsection extending toward said front and rear faces of said block andsaid first and second openings being defined by arm sections extendingoutwardly from a rear end of said stem section parallel to said frontface and toward respective sidewalls of said block.